Cells such as e.g. microorganisms are involved in numerous industrially relevant processes. for instance bacterial cultures, in particular cultures of bacteria that are generally classified as lactic acid bacteria (LAB) are essential in the marking of all fermented milk products, cheese and butter. Cultures of such bacteria may be referred to as started cultures and they impart specific features to various dairy products by performing a number of functions.
Many lactic acid bacteria are known to have probiotic properties (i.e. they have a beneficial health effect on humans when ingested). In most cases, it is imperative that the microorganisms remain viable after prolonged storage, in order for these to impart their beneficial effect on ingestion. Attempts have been made, in which freeze dried bacteria are mixed with additives that act as moist barriers, or as protectants needed for freezing the cells (so called cryo-protectants). Various types of additives have been added to the microorganisms in attempts to make them more stable.
For some uses—one may say that one preferably shall have a very storage stable lactic acid bacteria composition/formulation.
For instance—if the LAB composition is mixed with milk powder to make a suitable infant powder, one generally needs a very storage stable LAB composition—essentially due to than an infant powder product as such is normally very storage stable and may be given to infants quite a ling time after is actual fabrication date. Accordingly, if the infant powder is given to infants e.g. 30 weeks (or later) after its actual fabrication date—it is evident that the LAB composition incorporated into the infant powder should be quite storage stable in order to maintain viability of the LAB cells.
WO2010/138522A2 (Advanced Bionutrition Corporation) describes a LAB cell culture composition that is explained to be useful to be incorporated into an infant powder product.
A preferred composition comprises alginate, inulin, trehalose and hydrolyzed protein (see table 1, paragraph [0094]).
One may say that the LAB compositions of table 1 of WO2010/138522A2 comprise a relatively high amount of what may be termed protective agents—i.e. agent that could help to improve the storage stability of lactic acid bacteria cells.
For instance—one may say that the LAB compositions of table 1 of WO2010/138522A2 comprise a relatively high amount of trehalose.
Paragraph [0097] of WO2010/138522A2 reads:
“Lactobacillus Acidophilus (100 g frozen concentrate from a lab fermentation harvest) was thawed at 37 C. Protein hydrolysate premix (100 g, Table 1) . . . ”
As known to the skilled person, a LAB cell concentrate, as described in this paragraph [0097], may often comprise around 10% dry matter of cells. Under this assumption—one may say that the dried LAB composition described in this paragraph [0097] is a LAB composition that comprises around 10 times more protective agents than LAB cells as such—according to the art, this may be said to be a LAB composition with a relatively high amount of protective agents.
A problem with such LAB compositions with a relatively high amount of protective agents may be that they often can be quite difficult to properly dry as such—e.g. without significantly inactivation of the relevant LAB cells.
WO2010/138522A2 describes processes for drying e.g. the in paragraph [0097] described LAB composition, which as discussed above may say said to be a LAB composition with a relatively high amount of protective agents.
Paragraph [0081] of WO2010/138522A2 reads (emphasis added):
“Typical processes for preservation of bioactive microorganisms such as, live or attenuated organisms include a combination of freezing and vacuum conditions that can result in membrane damage and denaturation of cell constituents. The prior art teaches the use of higher vacuum pressures (e.g., less than 100 Torr), addition of specific cryoprotective agents, concentrating steps to obtain thick solutions (syrup), and/or higher initial temperatures to prevent freezing.”
This paragraph [0087] of WO2010/138522A2 may be said to provide an overall summary of what the prior art generally teaches with respect to suitable herein relevant drying processes.
It may herein be said to be relevant to note that the drying method directly and unambiguously described in WO2010/138522A2 is e.g. not involving a freezing step to form solid frozen particles/pellets.
WO2010/138522A2 (Advanced Bionutrition Corporation) describes a cell culture composition comprising alginate, inulin, trehalose and hydrolyzed protein (see table 1, paragraph [0094]).
However, there is still a need for improved compositions which are able to withstand elevated humidity/high water activity.